The present invention relates to a magneto-optical recording medium capable of direct overwriting in a light intensity modulation mode.
A magneto-optical (MO) recording medium is a recording medium wherein a magnetic thin film is locally heated by laser light or the like, and the magnetization direction of heated domains is reversed by an external magnetic field for recording, and these recorded domains having varying magnetization directions are read out by the Kerr effect, and the Faraday effect.
One feature of the magneto-optical recording medium is that recording density can be increased, and another feature is that, unlike a hard disk that is a mass storage magnetic recording medium, a medium replacement is easily achievable. However, a grave problem with an ordinary magneto-optical recording medium is that rewriting is slow, generally because overwriting cannot be used for rewriting; new information must be recorded after erasure of recorded information.
Magneto-optical recording media capable of direct overwriting by light intensity modulation (which may hereinafter be often called light intensity modulation overwriting), for instance, are disclosed in JP-A 62-175948, JP-B's 8-16993 and 8-16996, etc. For these magneto-optical media, however, it is required to built an initializing magnet in a driving device. On the other hand, magneto-optical recording media which is capable of light intensity modulation overwriting without recourse to any initializing magnet are disclosed in WO 90/02400, Japanese Patent No. 2503708, JP-A 6-12711, etc.